Smoke rises from an oil train derailment near Casselton, N.D., on Dec. 30

By Lisa Riordan Seville, NBC News

Top officials from the railroad and oil industries agreed Wednesday to consider voluntary new safety steps for oil trains carrying crude from the Bakken region of North Dakota – possibly including additional speed restrictions – in the wake of recent fiery crashes.

U.S. Transportation Secretary Anthony Foxx said the promise came at a meeting between federal regulators and top executives of North America’s largest railroads, a representative of smaller railroads and an official of the American Petroleum Institute to discuss safety concerns.

“The purpose of the meeting today was to reiterate the car safety mission and to call on the industry to take voluntary steps in the short term to help us ensure that this material is moving around the country as safely as possible,” Fox said at a news briefing following the two-hour meeting in Washington, D.C.

“The nation’s railroads share the administration’s sense of urgency and will collectively work to identify additional ways to make an already safe system even safer, Edward R. Hamberger, CEO of the Association of American Railroads, said in a statement after the meeting.

The rail industry pledged to look at a number of options over the next 30 days, including whether trains hauling crude should be subject to stricter routing and speed protocols required for trains hauling highly hazardous materials like explosive gasses, said Foxx, who attended the meeting along with the heads of the Federal Railroad Administration and the Pipeline and Hazardous Materials Safety Administration (PHMSA). It also would examine if further speed restrictions should be imposed in populated areas, he said.

Both industries also pledged to consider further improvements in the tank cars used to haul the crude, Foxx said. In the wake of the recent accidents, there have been widespread calls for improvements to the DOT-111 tank cars, the workhorse of the rail industry, which have for 20 years been found prone to rupture in derailments.

The Association of American Railroads issued revised standards for the DOT-111s in 2011, requiring a thicker shell and shields on either ends to help prevent punctures. But the new standard was not applied retroactively, meaning that only about 14,000 of the approximately 92,000 DOT-111 cars in service today are built to the new standards.

Both the railcar and oil industries, which build, lease and own the cars, have resisted calls to retrofit the remaining TK DOT-111s, citing the cost and years-long backlogs in tank building shops.

“The oil and natural gas industry will continue to work with regulators and the rail industry to make shipment by rail as safe as possible," API President and CEO Jack Gerard said in a statement provided to NBC News.

The oil industry also told regulators it would work with the PHMSA, the Transportation Department agency that monitors transport of dangerous materials, to share information on the content of the crude oil coming out of the Bakken region.

Concern over the transportation of the crude oil in the midst of an unprecedented domestic oil production boom has been growing in the wake of the derailments and explosions of four oil trains since July, including an accident in Lac Megantic, Quebec, that killed 47 people.

The explosions also have raised questions whether Bakken oil – a light, sweet crude extracted using new drilling methods, including “fracking” -- may be more flammable than traditional heavy crude.

Early this month federal regulators released a safety alert on the North Dakota oil and are currently conducting a series of tests dubbed the “Bakken Blitz” to establish its chemical makeup and flammability. The oil industry representative at Wednesday’s meeting also agreed that its members would share their own studies with regulators, Foxx said.